- tough, toughened - physically toughened; "the tough bottoms of his feet"
- tempered, treated, hardened, toughened - made hard or flexible or resilient especially by heat treatment; "a sword of tempered steel"; "tempered glass"
- toughen - make tough or tougher; "This experience will toughen her"
--1 is one way to strengthen
Sample sentences:
Somebody ----s something
Something ----s somebody
Something ----s something